The neuroanatomy research laboratory has been used this year for studies in the a) tracing of neuronal fiber connections in the brain, b) development of new in vitro autoradiography technique for localizing opiate and other peptide receptors in the brain, and c) localization of brain sites which are selectively involved in sleep and drug-induced sedation. The fiber-tracing technique, based on transport of tritiated amino acids, has been used to show by autoradiography a variety of laminar distributions of thalamic projections to cerebral cortex. These data provide structural evidence for mechanisms of thalamocortical integration. In addition, a new method for in vitro localization of brain receptors within slices of fresh-cut brain tissue is being developed. The technique has the potential for providing a simple and general way of visualizing sites of action of a wide range of biologically active substances in any fresh brain tissue. Receptor sites for opiate derivatives and benzodiazapines are currently under investigation. An third application of the autoradiographic technique will be to visualize brain areas with special functional and metabolic characteristics. Labeled 2-deoxy glucose may reveal brain sites that have special metabolic properties during sleep states following various forms of experiences by rats.